OPTIMALITY PROPERTIES OF MULTIPLE-KEY HASHING FUNCTIONS

All analysis of the achievable effictency of retrieval algorithms based on hashing for answermg partial-match queries is presented The remarkable power of hashing m hmmng the search of a given key value m a file is well known SLmilarly, R is possible to avoid searchmg major portions of a file m answering partialmatch or multlattnbute queries by hashing a multiattrlbute file into a number of buckets Multiple-key hashmg is a simple procedure for doing so and works by combining the effects of a number of hashing functions, one for each attribute m a record By usmg a measure of retrieval efficiency m which queries speofymg the same set of attributes are given equal weight, R is shown that mulUple-key hashmg often prowdes about the most efficient means of partmonmg a file for the purpose of answelrmg partial-match queries. © 1979, ACM. All rights reserved.